The objectives are to establish the sensitivity of pregnant ewes to the pressor effects of angiotensin II and to the depressor effects of bradykinin. Accurately timed gestations in Dorset sheep are utilized. At 119-121 days of gestation, electromagnetic flow transducers are placed on pertinent fetal and maternal vessels and catheters are placed into the maternal and fetal aorta and inferior vena cava. Leads are exteriorized and the animal is allowed to recover. Experiments are performed at a minimum of four days postoperatively to determine the responses of the uterine and umbilical vascular beds to these agents and to establish their tonic role in normal pregnancy.